1. Field of the Disclosure
The present disclosure relates to an image stabilization apparatus, an optical apparatus including the same, and an imaging apparatus.
2. Description of the Related Art
There has been proposed an imaging apparatus including an image stabilization apparatus that prevents image blur caused by an unintentional movement of hands during hand-held shooting. Japanese Patent Laid-Open No. 2007-219338 discloses an imaging apparatus including an image stabilization apparatus integrated with a light quantity regulating drive unit. The image stabilization apparatus provided in the imaging apparatus disclosed in Japanese Patent Laid-Open No. 2007-219338 includes a drive magnet that is integrally displaceable with a correction lens and a coil that displaces the drive magnet by an electromagnetic force. The image stabilization apparatus includes a feedback system constituted by a microcomputer, a coil, and a Hall element and repeatedly provides electricity through the coil while calculating the position of a correction lens holder after electricity is provided through the coil at a constant cycle to thereby perform camera-shake correction. The correction lens is brought into pressurized contact with a base serving as a fixing unit via a rolling ball.
Also, Japanese Patent Laid-Open No. 2007-232980 discloses a camera-shake correction device that detects a camera-shake amount and performs rotation/linear control of a movable unit provided in an X-Y movable stage in response to the detected camera-shake amount. The camera-shake correction device includes four ball bearings for holding the distance between the movable unit provided in the X-Y movable stage and a fixing unit at a certain level. Also, the camera-shake correction device includes a plurality of electromagnetic actuators that are driven in the X direction or the Y direction.
However, in the image stabilization apparatus disclosed in Japanese Patent Laid-Open No. 2007-219338, if an attempt to increase output (torque) by increasing the size of an electromagnetic actuator (magnet 21a and coil 22a) is made, it becomes difficult to ensure a ball receiving surface supporting a movable unit. In other words, in the image stabilization apparatus disclosed in Japanese Patent Laid-Open No. 2007-219338, the ball receiving surface needs to be ensured, and thus, the output of the electromagnetic actuator cannot be increased. Also, in the image stabilization apparatus, the size of each of the drive magnet and the coil is appropriately set so as to be drivable within a predetermined range required for correcting image blur depending on the weight of the movable unit including the correction lens. In other words, if the movable unit is heavy or the amount of movement required for correcting image blur becomes large, the sizes of both the drive magnet and the coil tend to be increased by that amount. Consequently, the entire image stabilization apparatus cannot be reduced in size.
Also, in the camera-shake correction device disclosed in Japanese Patent Laid-Open No. 2007-232980, four ball bearings are arranged at locations avoiding the electromagnetic actuator. In other words, the camera-shake correction device is supported by four points. However, the plane is geometrically defined by three points. Hence, the fourth point becomes a non-contact point unless the fourth point is configured as precise as possible. If the error in position at the fourth point occurs, the camera-shake correction device may be brought into contact or non-contact with the fourth point. Thus, the camera-shake correction device disclosed in Japanese Patent Laid-Open No. 2007-232980 is supported by four points, resulting in a rattling movement each time the movable unit is driven.
Furthermore, in the camera-shake correction device disclosed in Japanese Patent Laid-Open No. 2007-232980, a plurality of electromagnetic actuators is provided. Hence, if the camera-shake correction device is supported by three points provided at locations avoiding these electromagnetic actuators, the following problem may arise. In other words, the support position can only be provided at an unbalanced position relative to the centroid of the movable unit or the support position must be arranged on the outer side or the inner side of the electromagnetic actuators. Consequently, the entire device is increased in size.